- curses terminal input option control routines
cc [ flag ... ] file ... -lcurses [ library ... ] #include <curses.h> int cbreak(void);
int halfdelay(int tenths);
int intrflush(WINDOW *win, bool bf);
int keypad(WINDOW *win, bool bf);
int meta(WINDOW *win, bool bf);
int nodelay(WINDOW *win, bool bf);
int notimeout(WINDOW *win, bool bf);
void timeout(int delay);
void wtimeout(WINDOW *win, int delay);
int typeahead(int fildes);
The cbreak() and nocbreak() routines put the terminal into and out of cbreak() mode, respectively. In this mode, characters typed by the user are immediately available to the program, and erase/kill character-processing is not performed. When out of this mode, the tty driver buffers the typed characters until a newline or carriage return is typed. Interrupt and flow control characters are unaffected by this mode. Initially the terminal may or may not be in cbreak() mode, as the mode is inherited; therefore, a program should call cbreak() or nocbreak() explicitly. Most interactive programs using curses set the cbreak() mode.
Note that cbreak() overrides raw(). (See curs_getch(3CURSES) for a discussion of how these routines interact with echo() and noecho().)
The echo() and noecho() routines control whether characters typed by the user are echoed by getch() as they are typed. Echoing by the tty driver is always disabled, but initially getch() is in echo mode, so characters typed are echoed. Authors of most interactive programs prefer to do their own echoing in a controlled area of the screen, or not to echo at all, so they disable echoing by calling noecho(). (See curs_getch(3CURSES) for a discussion of how these routines interact with cbreak() and nocbreak().)
The halfdelay() routine is used for half-delay mode, which is similar to cbreak() mode in that characters typed by the user are immediately available to the program. However, after blocking for tenths tenths of seconds, ERR is returned if nothing has been typed. The value of tenths must be a number between 1 and 255. Use nocbreak() to leave half-delay mode.
If the intrflush() option is enabled, (bf is TRUE), when an interrupt key is pressed on the keyboard (interrupt, break, quit) all output in the tty driver queue will be flushed, giving the effect of faster response to the interrupt, but causing curses to have the wrong idea of what is on the screen. Disabling (bf is FALSE), the option prevents the flush. The default for the option is inherited from the tty driver settings. The window argument is ignored.
The keypad() option enables the keypad of the user's terminal. If enabled (bf is TRUE), the user can press a function key (such as an arrow key) and wgetch() returns a single value representing the function key, as in KEY_LEFT. If disabled (bf is FALSE), curses does not treat function keys specially and the program has to interpret the escape sequences itself. If the keypad in the terminal can be turned on (made to transmit) and off (made to work locally), turning on this option causes the terminal keypad to be turned on when wgetch() is called. The default value for keypad is false.
Initially, whether the terminal returns 7 or 8 significant bits on input depends on the control mode of the tty driver (see termio(7I)). To force 8 bits to be returned, invoke meta(win, TRUE). To force 7 bits to be returned, invoke meta(win, FALSE). The window argument, win, is always ignored. If the terminfo capabilities smm (meta_on) and rmm (meta_off) are defined for the terminal, smm is sent to the terminal when meta( win, TRUE) is called and rmm is sent when meta(win, FALSE) is called.
The nodelay() option causes getch() to be a non-blocking call. If no input is ready, getch() returns ERR. If disabled (bf is FALSE), getch() waits until a key is pressed.
While interpreting an input escape sequence, wgetch() sets a timer while waiting for the next character. If notimeout(win, TRUE) is called, then wgetch() does not set a timer. The purpose of the timeout is to differentiate between sequences received from a function key and those typed by a user.
With the raw() and noraw() routines, the terminal is placed into or out of raw mode. Raw mode is similar to cbreak() mode, in that characters typed are immediately passed through to the user program. The differences are that in raw mode, the interrupt, quit, suspend, and flow control characters are all passed through uninterpreted, instead of generating a signal. The behavior of the BREAK key depends on other bits in the tty driver that are not set by curses.
When the noqiflush() routine is used, normal flush of input and output queues associated with the INTR, QUIT and SUSP characters will not be done (see termio(7I)). When qiflush() is called, the queues will be flushed when these control characters are read.
The timeout() and wtimeout() routines set blocking or non-blocking read for a given window. If delay is negative, blocking read is used (that is, waits indefinitely for input). If delay is zero, then non-blocking read is used (that is, read returns ERR if no input is waiting). If delay is positive, then read blocks for delay milliseconds, and returns ERR if there is still no input. Hence, these routines provide the same functionality as nodelay(), plus the additional capability of being able to block for only delay milliseconds (where delay is positive).
curses does ``line-breakout optimization'' by looking for typeahead periodically while updating the screen. If input is found, and it is coming from a tty, the current update is postponed until refresh() or doupdate() is called again. This allows faster response to commands typed in advance. Normally, the input FILE pointer passed to newterm(), or stdin in the case that initscr() was used, will be used to do this typeahead checking. The typeahead() routine specifies that the file descriptor fildes is to be used to check for typeahead instead. If fildes is -1, then no typeahead checking is done.
All routines that return an integer return ERR upon failure and an integer value other than ERR upon successful completion, unless otherwise noted in the preceding routine descriptions.
See attributes(5) for descriptions of the following attributes:
The header <curses.h> automatically includes the headers <stdio.h> and <unctrl.h>.
Note that echo(), noecho(), halfdelay(), intrflush(), meta(), nodelay(), notimeout(), noqiflush(), qiflush(), timeout(), and wtimeout() may be macros.